Untreated lumber for uncovered deck?

[woody]

Just my two cents, if I were in your situation as in owning the mill and the trees I would use some white oak and enjoy a solid deck for years.

 

[Doughknob]

You "can" use pine, or anything else --- if you properly treat and care for it. Stain itself will not work. You'd have to use a good outdoor varnish or paint. And you'd have to re-apply every few years. The idea is to keep rain and, more importantly sun, from direct contact. The topcoats like varnish or paint will do this if maintained.

So, to clarify - paint does work, assuming the top surface is painted. As the poster below said, the wood can still breathe if the bottom surface is unpainted. Or like on old houses or barns with wood siding, the 'inner' surface is not painted.

 

[Egon]

Coat with a preservative first. Then a stain. No paint. The coatings applied should be able to breath and not restrict the passage of moisture.

Both products are readily available at regular stores.

 

[RalphVa]

Whatever you do, do not use a stain that is more like a paint. It holds moisture in and causes the wood, even treated wood, to decay.

We're replacing our boards and rail tops with PVC called Azek. Had a stain on the treated wood, and it just went to pot. Had to replace most of the screws with stainless because they were corroding.

Red cedar would be my first choice.

 

[skipmarcy]

I would tend to agree that the white oak would be better, red oak rots more easily and bugs go for it more too. If I were going to do this project I would use a couple of coats of oil based stain or preservative and let it dry well. Then I would use spar varnish on the top surfaces with some sort of traction material added. You may not want this type of finish for your surface though.

The red cedar would certainly hold up but it's going to go gray without the spar varnish or some sort of good UV protection. I've been considering cutting my 7 very large red cedar trees for years now to make lumber but I hate to see them go and am getting too old & tired to be messing with sawmill lumber anymore. My trees are approx. 20"+ in diameter and quite tall - could get 2 or maybe 3 decent 8' or 10' logs out of each one.

 

[ponytug]

@N80 How big is this deck? If it isn't that big, I would go with your downed oak.

Slashleaf pine (one of four species called southern yellow pine) is a wonderful wood, and quite strong, and would also make a great deck.

I love cedar for paneling, fence posts, and trunks. For weight bearing use on a deck, I am much less excited, as it has a tendency to fracture. If you have ever seen someone step through a deck, it is ugly, as the knee jerk response is to jerk the leg up, thereby driving the wood splinters into the leg. You would need to oversize the cedar dimension by about two fold to get to the strength of pine, and even then it tends to fail completely, rather than cracking.

Copper sulfate will stain your wood, and won't do much for preservation, as you can't get very much into the wood. Copper naphthalenate is available, but it will stain everything dark green, including you, and stinks to high heaven.

One comment on oil vs varnish; you do need to re-treat the deck with linseed oil (or whatever clear stain you decide to use) every couple of years depending on sun exposure. With a sprayer, or a roller, it goes really quickly. Varnish is, in my experience, much higher maintenance and can need sanding and varnishing annually in high exposure areas. Don't get me wrong, I love the look of varnish, but it isn't do it once and forget it. If you change your mind after varnishing, it would mean sanding the whole deck down.

On the subject of stains; don't waste your money on a water based stain for a deck, that really won't last, contrary to what the can says. It has no penetration, and so no endurance. I think they are marginal for fences, and that is about their only use. (Who me, opinionated?)

Good luck!

All the best,

Peter

 

[EddieWalker]

Here in East Texas, pressure treated deck boards are lucky to last a decade. Everything else usually rots away even faster. But something that I've noticed is that when I've made some emergancy, temporary fencing repairs with regular 2x4s and 2x6s is that after years out in the weather, they are still solid. None touch the ground. All are almost totally surrounded by air and they are installed on the edge so water never sits on them. I plan to replace them, but I'm also curious to see how long they last. The oldest one has been there since 2013.

 

[BigBlue1]

Well, Rust-Oleum makes a product called Creo-Coat that is great for preserving and protecting untreated wood, above or below ground. But it is black and likely not something you'd want on a deck.

 

[Captain Dirty]

Yankee redneck solution (likely not EPA approved). Dig a shallow trench or build a wooden frame, line same with 6-mill poly, place board(s) in trench or frame and cover with used crankcase oil. Will also have to cobble together a rack or pan with grating to let the treated boards drain/dry. Painting or further treatment not practicable.

 

[Captain Dirty]

Do not underestimate the durability of "natural" or "older" growth wood when compared to the "forced" growth of plantation-grown trees. A friend trimmed his house with eastern white pine milled from "natural" trees on his property. Others told him it would last 3-5 years, max. Forty years later it is still fine. He did prime 6 sides and painted the exposed sides.